package network;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: Li_DaChiZi
 * Date: 2025/7/11
 * Time: 10:10
 */
public class UdpEchoServer {
    private DatagramSocket socket = null;

    public UdpEchoServer (int port) throws SocketException {
        socket = new DatagramSocket(port);
    }

    public void start() throws IOException {
        System.out.println("服务器启动!");
        while (true) {
            // 此处通过死循环，不断处理客户端请求

            //1.读取客户端请求
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            //上述收到的数据，是二进制byte[] 形式体现的，后续代码如果要打印，需要转成字符串来体现。
            String request = new String(requestPacket.getData(),0,requestPacket.getLength());

            // 2. 根据请求进行响应
            String response = process(request);

            // 3. 把响应写回给客户端
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(), response.getBytes().length,
                    requestPacket.getSocketAddress());
            socket.send(responsePacket);

            // 4. 打印日志
            System.out.printf("[%s:%d] req = %s, resp = %s\n", requestPacket.getAddress(), requestPacket.getPort(),
                    request, response);
        }
    }

    public String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoServer server = new UdpEchoServer(9090);
        server.start();

    }
}
